As such, it can be seen as two things:
A virtual desktop manager for Samurize (with a little help from VirtuaWin)
A skinnable interface for VirtuaWin (with a little help from Samurize)
VirtuaWin has no graphical interface of its own. It is controlled with the keyboard or through a systray icon, or as in this case, with an external application. This makes it an ideal companion for Samurize, providing virtual desktops integrated in your Samurize config.